PLS-00382: expression is of wrong type in populating an associative array table - plsql

Question

I have this structure of table in my database
Now i want all the values inside of it in a associative array that is indexed by the job_id%type which is a varchar2, so i created this anonymous block first before creating a procedure to test it and i want to populate my associative array with the results:
DECLARE
TYPE jobs_tab_type IS TABLE OF jobs%rowtype INDEX BY jobs.job_id%type;
jobstab jobs_tab_type;
BEGIN
FOR rec IN (SELECT * FROM jobs)
LOOP
jobstab(rec.job_id) := rec.job_id;
END LOOP;
END;
I know for sure that this is a wrong way to do it since I've encountered this error: PLS-00382: expression is of wrong type , but at the same time i don't know if there is any proper way to do this. I have seen the documentation but all the examples were to use a user defined string that will hold the job_id, but the problem is that i need the job_id to be indexed and not a user defined string. Is there any way to fix this problem in PL/SQL?

Answer 1

You don't need the index by INDEX BY jobs.job_id%type. It is making your code more complicated. The INDEX BY determines the index of the collection - that is the character used to indicate the position in the collection. That doesn't need to be a column from the table you are taking a %rowtype from.
Typically an INDEX BY VARCHAR2 is used if you want to reference the collection based on a meaningful string, like capitals('United States') = 'Washingston'
Now, about your question. Here is the answer to the original question:
create table jobs
(job_id VARCHAR2(10)
,job_title VARCHAR2(30)
,min_salary NUMBER
,max_salary NUMBER
);
INSERT INTO jobs (job_id, job_title, min_salary, max_salary) VALUES ('a','CLERK',100,500);
INSERT INTO jobs (job_id, job_title, min_salary, max_salary) VALUES ('b','PRESIDENT',1000,5000);
INSERT INTO jobs (job_id, job_title, min_salary, max_salary) VALUES ('c','SALESMAN',500,800);
DECLARE
TYPE jobs_tab_type IS TABLE OF jobs%rowtype INDEX BY jobs.job_id%type;
jobstab jobs_tab_type;
l_idx VARCHAR2(100);
BEGIN
FOR rec IN (SELECT * FROM jobs)
LOOP
jobstab(rec.job_id) := rec;
END LOOP;
l_idx := jobstab.FIRST;
WHILE (l_idx IS NOT NULL) LOOP
dbms_output.put_line(l_idx ||': '||jobstab(l_idx).job_title);
l_idx := jobstab.NEXT(l_idx);
END LOOP;
END;
/
a: CLERK
b: PRESIDENT
c: SALESMAN
Notice that in this block, it's a bit tedious to loop through the elements, just because the index is not an integer. Now lets look at the same functionality, but using an INDEX BY BINARY_INTEGER:
DECLARE
TYPE jobs_tab_type IS TABLE OF jobs%rowtype INDEX BY BINARY_INTEGER;
jobstab jobs_tab_type;
l_idx NUMBER := 1;
BEGIN
-- example 1: using a cursor for loop
-- FOR rec IN (SELECT * FROM jobs)
-- LOOP
-- jobstab(l_idx) := rec;
-- l_idx := l_idx + 1;
-- END LOOP;
-- example 2: using bulk collect
SELECT * BULK COLLECT INTO jobstab FROM jobs;
FOR r IN 1 .. jobstab.COUNT LOOP
dbms_output.put_line(r ||': '||jobstab(r).job_title);
END LOOP;
END;
/
1: CLERK
2: PRESIDENT
3: SALESMAN
It's simpler to loop through the values of a collection because of the numeric index and it also can be implicitly assigned as well, using the BULK COLLECT statement.

Answer 2

The value of your associative array is the entire record. Hence just remove .job_id from this line of your code.
jobstab(rec.job_id) := rec.job_id;
In other words, the line should be
jobstab(rec.job_id) := rec;
Refer to this db<>fiddle